Hybrid corn plant and seed (3531)

ABSTRACT

According to the invention, there is provided a hybrid corn plant, designated as 3531, produced by crossing two Pioneer Hi-Bred International, Inc. proprietary inbred corn lines. This invention thus relates to the hybrid seed 3531, the hybrid plant produced from the seed, and variants, mutants, and trivial modifications of hybrid 3531. 3531 is characterized by its high yielding and solid agronomics. 3531 has above average yield across all yield environments and responds to high planting rates.

FIELD OF THE INVENTION

This invention is in the field of corn breeding, specifically relating to an hybrid corn plant and seed designated 3531.

BACKGROUND OF THE INVENTION Plant Breeding

Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinated if pollen from one flower is transferred to the same or another flower of the same plant. A plant is cross-pollinated if the pollen comes from a flower on a different plant.

Corn plants (Zea mays L.) can be bred by both self-pollination and cross-pollination techniques. Corn has separate male and female flowers on the same plant, located on the tassel and the ear, respectively. Natural pollination occurs in corn when wind blows pollen from the tassels to the silks that protrude from the tops of the incipient ears.

The development of a hybrid corn variety involves three steps: (1) the selection of plants from various germplasm pools; (2) the selfing of the selected plants for several generations to produce a series of inbred lines, which, although different from each other, breed true and are highly uniform; and (3) crossing the selected inbred lines with unrelated inbred lines to produce the hybrid progeny (F₁). During the inbreeding process in corn, the vigor of the lines decreases. Vigor is restored when two unrelated inbred lines are crossed to produce the hybrid progeny. An important consequence of the homozygosity and homogeneity of the inbred lines is that the hybrid between a defined pair of inbreds will always be the same. Once the inbreds that give a superior hybrid have been identified, the hybrid seed can be reproduced indefinitely as long as the homogeneity of the inbred parents is maintained.

Hybrid corn seed can be produced by manual detasseling. Alternate strips of two inbred varieties of corn are planted in a field, and the pollen-bearing tassels are removed from one of the inbreds (female). Providing that there is sufficient isolation from sources of foreign corn pollen, the ears of the detasseled inbred will be fertilized only from pollen from the other inbred (male), and the resulting seed is therefore hybrid and will form hybrid plants.

The laborious detasseling process can be avoided by using male-sterile inbreds. Plants of these inbreds are fertilized with pollen from another inbred that is not male-sterile. Pollen from the second inbred can contribute genes that make the hybrid plants male-fertile. Usually seed from detasseled normal corn and male sterile produced seed of the same hybrid is blended to insure that adequate pollen loads are available for fertilization when the hybrid plants are grown.

The objective of commercial maize hybrid line development programs is to develop new inbred lines to produce hybrids that combine to produce high grain yields and superior agronomic performance. The primary trait breeders seek is yield. However, other major agronomic traits are of importance in hybrid combination and have an impact on yield or otherwise provide superior performance in hybrid combinations. Such traits include percent grain moisture at harvest, relative maturity, resistance to stalk breakage, resistance to root lodging, grain quality, and disease and insect resistance. In addition the lines per se must have acceptable performance for parental traits such as seed yields, kernel sizes, pollen production, all of which affect ability to provide parental lines in sufficient quantity and quality for hybridization. These traits have been shown to be under genetic control and many if not all of the traits are affected by multiple genes.

Pedigree Breeding

The pedigree method of breeding is the mostly widely used methodology for new hybrid line development.

In general terms this procedure consists of crossing two inbred lines to produce the non-segregating F₁ generation, and self pollination of the F₁ generation to produce the F₂ generation that segregates for all factors for which the inbred parents differ. An example of this process is set forth below. Variations of this generalized pedigree method are used, but all these variations produce a segregating generation which contains a range of variation for the traits of interest.

EXAMPLE 1 Hypothetical Example of Pedigree Breeding Program

Consider a cross between two inbred lines that differ for alleles at five loci. The parental genotypes are:

    ______________________________________     Parent 1        A b C d e F/A b C d e F     Parent 2        a B c D E f/a B c D E f     ______________________________________

the F₁ from a cross between these two parents is:

    ______________________________________     A b C d e F/a B c D E f     ______________________________________

Selfing F₁ will produce an F₂ generation including the following genotypes:

    ______________________________________              A B c D E f/a b C d e F              A B c D e f/a b C d E F              A B c D e f/a b C d e F              .              .              .     ______________________________________

The number of genotypes in the F₂ is 3⁶ for six segregating loci (729) and will produce (2⁶)-2 possible new inbreds, (62 for six segregating loci).

Each inbred parent which is used in breeding crosses represents a unique combination of genes, and the combined effects of the genes define the performance of the inbred and its performance in hybrid combination. There is published evidence (Smith, O. S., J. S. C. Smith, S. L. Bowen, R. A. Tenborg and S. J. Wall, TAG 80:833-840 (1990)) that each of these lines are different and can be uniquely identified on the basis of genetically-controlled molecular markers.

It has been shown (Hallauer, Arnel R. and Miranda, J. B. Fo. Quantitative Genetics in Maize Breeding, Iowa State University Press, Ames Iowa, 1981) that most traits of economic value in maize are under the genetic control of multiple genetic loci, and that there are a large number of unique combinations of these genes present in elite maize germplasm. If not, genetic progress using elite inbred lines would no longer be possible. Studies by Duvick and Russell (Duvick, D. N., Maydica 37:69-79, (1992); Russell, W. A., Maydica XXIX:375-390 (1983)) have shown that over the last 50 years the rate of genetic progress in commercial hybrids has been between 1 and 2% per year.

The number of genes affecting the trait of primary economic importance in maize, grain yield, has been estimated to be in the range of 10-1000. Inbred lines which are used as parents for breeding crosses differ in the number and combination of these genes. These factors make the plant breeder's task more difficult. Compounding this is evidence that no one line contains the favorable allele at all loci, and that different alleles have different economic values depending on the genetic background and field environment in which the hybrid is grown. Fifty years of breeding experience suggests that there are many genes affecting grain yield and each of these has a relatively small effect on this trait. The effects are small compared to breeders' ability to measure grain yield differences in evaluation trials. Therefore, the parents of the breeding cross must differ at several of these loci so that the genetic differences in the progeny will be large enough that breeders can develop a line that increases the economic worth of its hybrids over that of hybrids made with either parent.

If the number of loci segregating in a cross between two inbred lines is n, the number of unique genotypes in the F₂ generation is 3^(n) and the number of unique inbred lines from this cross is {(2^(n))-2}. Only a very limited number of these combinations are useful. Only about 1 in 10,000 of the progeny from F₂ 's are commercially useful.

By way of example, if it is assumed that the number of segregating loci in F₂ is somewhere between 20 and 50, and that each parent is fixed for half the favorable alleles, it is then possible to calculate approximate probabilities of finding an inbred that has the favorable allele at {(n/2)+m} loci, where n/2 is the number of favorable alleles in each of the parents and m is the number of additional favorable alleles in the new inbred. See Example 2 below. The number m is assumed to be greater than three because each allele has so small an effect that evaluation techniques are not sensitive enough to detect differences due to three or less favorable alleles. The probabilities in Example 2 are on the order of 10⁻⁵ or smaller and they are the probabilities that at least one genotype with (n/2)+m favorable alleles will exist.

To put this in perspective the number of plants grown on 60 million acres (approximate U.S. corn acreage) at 25000 plants/acre is 1.5×10¹².

EXAMPLE 2 Probability of Finding an Inbred With m Of n Favorable Alleles

Assume each parent has n/2 of the favorable alleles and only 1/2 of the combinations of loci are economically useful.

    ______________________________________     no. of   no. favorable                         no. additional                                       Probability     segregating              alleles in favorable alleles                                       that geno-     loci (n) Parents (n/2)                         in new inbred type occurs*     ______________________________________     20       10         14            3 × 10.sup.-5     24       12         16            2 × 10.sup.-5     28       14         18            1 × 10.sup.-5     32       16         20            8 × 10.sup.-6     36       18         22            5 × 10.sup.-6     40       20         24            3 × 10.sup.-6     44       22         26            2 × 10.sup.-6     48       24         28            1 × 10.sup.-6     ______________________________________

The possibility of having a usably high probability of being able to identify this genotype based on replicated field testing would be most likely smaller than this, and is a function of how large a population of genotypes is tested and how testing resources are allocated in the testing program.

At Pioneer Hi-Bred International, a typical corn research station has a staff of four, and 20 acres of breeding nursery. Those researchers plant those 20 acres with 25,000 nursery rows, 15,000 yield test plots in 10-15 yield test sites, and one or two disease-screening nurseries. Employing a temporary crew of 20 to 30 pollinators, the station makes about 65,000 hand pollinations per growing season. Thus, one of the largest plant breeding programs in the world does not have a sufficiently large breeding population to be able to rely upon "playing the numbers" to obtain successful research results. Nevertheless, Pioneer's breeders at each station produce from three to ten new inbreds which are proposed for commercial use each year. Over the 32 Pioneer research stations in North America, this amounts to from about 100 to 300 new inbreds proposed for use, and less than 50 and more commonly less than 30 of these inbreds that actually satisfy the performance criteria for commercial use.

This is a result of plant breeders using their skills, experience, and intuitive ability to select inbreds having the necessary qualities so that improved hybrids may be produced.

SUMMARY OF THE INVENTION

According to the invention, there is provided a hybrid corn plant, designated as 3531, produced by crossing two Pioneer Hi-Bred International, Inc. proprietary inbred corn lines; a first inbred corn line designated PHTE4, described in U.S. Pat. No. 5,453,564, to be issued Sep. 26, 1995, and in co-pending patent applications, Ser. No. 08/414,477, filed Mar. 31, 1995, and Ser. No. 08/500,286, filed Jul. 10, 1995, having ATCC accession number 97065, and a second inbred corn line designated PHP55, described in issued U.S. Pat. No. 5,159,134 and having ATCC accession number 75220. This invention thus relates to the hybrid seed 3531, the hybrid plant produced from the seed, and variants, mutants and trivial modifications of hybrid 3531. This hybrid corn plant is characterized by excellent yield for maturity and good stalks. 3531 has very good stand establishment and is higher in protein yield than other hybrids in its maturity. 3531 has above average performance across all yield environments and responds very well to high yield environments. 3531 has very good resistance to levels of Goss' Wilt and Head Smut. 3531 also has above average resistance to both first and second brood European Corn Borer infestations.

DEFINITIONS

In the description and examples that follow, a number of terms are used herein. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided. ABS is in absolute terms and % MN is percent of the mean for the experiments in which the inbred or hybrid was grown.

BAR PLT=BARREN PLANTS. The percent of plants per plot that were not barren (lack ears).

BRT STK=BRITTLE STALKS. This is a measure of the stalk breakage near the time of pollination, and is an indication of whether a hybrid or inbred would snap or break near the time of flowering under severe winds. Data are presented as percentage of plants that did not snap.

BU ACR=YIELD (BUSHELS/ACRE). Actual yield of the grain at harvest in bushels per acre adjusted to 15.5% moisture.

DRP EAR=DROPPED EARS. A measure of the number of dropped ears per plot and represents the percentage of plants that did not drop ears prior to harvest.

EAR HT=EAR HEIGHT. The ear height is a measure from the ground to the highest placed developed ear node attachment and is measured in inches.

EAR SZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher the rating the larger the ear size.

EST CNT=EARLY STAND COUNT. This is a measure of the stand establishment in the spring and represents the number of plants that emerge on a per plot basis for the inbred or hybrid.

GDU SHD=GDU TO SHED. The number of growing degree units (GDUs) or heat units required for an inbred line or hybrid to have approximately 50 percent of the plants shedding pollen and is measured from the time of planting. Growing degree units are calculated by the Barger Method, where the heat units for a 24-hour period are: ##EQU1##

The highest maximum temperature used is 86° F. and the lowest minimum temperature used is 50° F. For each inbred or hybrid it takes a certain number of GDUs to reach various stages of plant development.

GDU SLK=GDU TO SILK. The number of growing degree units required for an inbred line or hybrid to have approximately 50 percent of the plants with silk emergence from time of planting. Growing degree units are calculated by the Barger Method as given in GDU SHD definition.

GRN APP=GRAIN APPEARANCE. This is a 1 to 9 rating for the general appearance of the shelled grain as it is harvested based on such factors as the color of the harvested grain, any mold on the grain, and any cracked grain. High scores indicate good grain quality.

MST=HARVEST MOISTURE. The moisture is the actual percentage moisture of the grain at harvest.

PLT HT=PLANT HEIGHT. This is a measure of the height of the plant from the ground to the tip of the tassel in inches.

POL SC=POLLEN SCORE. A 1 to 9 visual rating indicating the amount of pollen shed. The higher the score the more pollen shed.

POL WT=POLLEN WEIGHT. This is calculated by dry weight of tassels collected as shedding commences minus dry weight from similar tassels harvested after shedding is complete.

It should be understood that the inbred can, through routine manipulation of cytoplasmic factors, be produced in a cytoplasmic male-sterile form which is otherwise phenotypically identical to the male-fertile form.

PRM=PREDICTED RM. This trait, predicted relative maturity (RM), is based on the harvest moisture of the grain. The relative maturity rating is based on a known set of checks and utilizes standard linear regression analyses and is referred to as the Comparative Relative Maturity Rating System which is similar to the Minnesota Relative Maturity Rating System.

RT LDG=ROOT LODGING. Root lodging is the percentage of plants that do not root lodge; plants that lean from the vertical axis at an approximately 30° angle or greater would be counted as root lodged.

SCT GRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount of scatter grain (lack of pollination or kernel abortion) on the ear. The higher the score the less scatter grain.

SDG VGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amount of vegetative growth after emergence at the seedling stage (approximately five leaves). A higher score indicates better vigor.

SEL IND=SELECTION INDEX. The selection index gives a single measure of the hybrid's worth based on information for up to five traits. A corn breeder may utilize his or her own set of traits for the selection index. One of the traits that is almost always included is yield. The selection index data presented in the tables represent the mean value averaged across testing stations.

STA GRN=STAY GREEN. Stay green is the measure of plant health near the time of black layer formation (physiological maturity). A high score indicates better late-season plant health.

STK CNT=NUMBER OF PLANTS. This is the final stand or number of plants per plot.

STK LDG=STALK LODGING. This is the percentage of plants that did not stalk lodge (stalk breakage) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.

TAS BLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure the degree of blasting (necrosis due to heat stress) of the tassel at time of flowering. A 1 would indicate a very high level of blasting at time of flowering, while a 9 would have no tassel blasting.

TAS SZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate the relative size of the tassel. The higher the rating the larger the tassel.

TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams) just prior to pollen shed.

TEX EAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate the relative hardness (smoothness of crown) of mature grain. A 1 would be very soft (extreme dent) while a 9 would be very hard (flinty or very smooth crown).

TILLER=TILLERS. A count of the number of tillers per plot that could possibly shed pollen was taken. Data is given as percentage of tillers: number of tillers per plot divided by number of plants per plot.

TST WT=TEST WEIGHT (UNADJUSTED). The measure of the weight of the grain in pounds for a given volume (bushel).

TST WTA=TEST WEIGHT ADJUSTED. The measure of the weight of the grain in pounds for a given volume (bushel) adjusted for percent moisture.

YLD=YIELD. It is the same as BU ACR ABS.

YLD SC=YIELD SCORE. A 1 to 9 visual rating was used to give a relative rating for yield based on plot ear piles. The higher the rating the greater visual yield appearance.

MDM CPX=Maize Dwarf Mosaic Complex (MDMV=Maize Dwarf Mosaic Virus & MCDV=Maize Chlorotic Dwarf Virus): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

SLF BLT=Southern Leaf Blight (Bipolaris maydis, Helminthosporium maydis): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

NLF BLT=Northern Leaf Blight (Exserohilum turcicum, H. turcicum): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

COM RST=Common Rust (Puccinia sorghi): visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

GLF SPT=Gray Leaf Spot (Cercospora zeae-maydis): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

STW WLT=Stewart's Wilt (Erwinia stewartii): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

HD SMT=Head Smut (Sphacelotheca reiliana): Percentage of plants that did not have infection.

EAR MLD=General Ear Mold: Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant. This is based on overall rating for ear mold of mature ears without determining specific mold organism, and may not be predictive for a specific ear mold.

ECB DPE=Dropped ears due to European Corn Borer (Ostrinia nubilalis): Percentage of plants that did not drop ears under second brood corn borer infestation.

ECB 2SC=European Corn Borer Second Brood (Ostrinia nubilalis): Visual rating (1-9 score) of post flowering damage due to infestation by European Corn Borer. A "1" is very susceptible and a "9" is very resistant.

ECB 1LF=European Corn Borer First Brood (Ostrinia nubilalis): Visual rating (1-9 score) of pre-flowering leaf feeding by European Corn Borer. A "1" is very susceptible and a "9" is very resistant.

DETAILED DESCRIPTION OF THE INVENTION

Pioneer Brand Hybrid 3531 has outstanding yield and has good potential as a silage hybrid, having good total plant yield and digestability. Its early flowering and black layer should allow it to move North. 3531 has good early growth, above average brittle stalk resistance and excellent Goss' wilt resistance. The hybrid shows good resistance to common rust. 3531 has average stalk lodging resistance. It has slightly below average test weight.

Pioneer Brand Hybrid 3531 is a single cross, yellow endosperm, dent corn hybrid with outstanding yield in its maturity. 3531 has stable yield across environments and flowers and black layers early.

This hybrid has the following characteristics based on the descriptive data collected primarily at Johnston, Iowa.

VARIETY DESCRIPTION INFORMATION Hybrid=Pioneer Brand 3531

Type: Dent, Region Best Adapted: Central Corn Belt

A. Maturity:

Minnesota Relative Maturity Rating (harvest moisture): 105

GDU's to Physiological Maturity (black layer): 2490

GDU's to 50% Silk: 1260 ##EQU2##

B. Plant Characteristics:

Plant height (to tassel tip): 272 cm

Length of top ear internode: 21 cm

Number of ears per stalk: Single

Ear height (to base of top ear): 76 cm

Number of tillers: None

Cytoplasm type: Normal

C. Leaf:

Color: (B14) Dark Green

Angle from Stalk: <30 degrees

Marginal Waves: (OH7L) Many

Number of Leaves (mature plants): 19

Sheath Pubescence: (W22) Light

Longitudinal Creases: (PA11) Many

Length (Ear node leaf): 88 cm

Width (widest point, ear node leaf): 10 cm

D. Tassel:

Number lateral branches: 7

Branch Angle from central spike: >45 degrees

Pollen Shed: (KY21) Heavy

Peduncle Length (top leaf to basal branches): 24 cm

Anther Color: Purple

Glume Color: Green

E. Ear (Husked Ear Data Except When Stated Otherwise):

Length: 20 cm

Weight: 186 gm

Mid-point Diameter: 46 mm

Silk Color: Salmon

Husk Extension (Harvest stage): Medium (Barely Covering Ear)

Husk Leaf: Long (>15 cm)

Taper of Ear: Average

Position of Shank (dry husks): Upright

Kernel Rows: Slightly Curved Distinct Number=14

Husk Color (fresh): Light Green

Husk Color (dry): Buff

Shank Length: 9 cm

Shank (No. of internodes): 7

F. Kernel (Dried):

Size (from ear mid-point)

Length: 13 mm

Width: 9 mm

Thick: 5 mm

Shape Grade (% rounds): N/A

Pericarp Color: Colorless

Aleurone Color: Homozygous Yellow

Endosperm Color: Yellow

Endosperm Type: Normal Starch

Gm Wt/100 Seeds (unsized): 28 gm

G. Cob:

Diameter at mid-point: 26 mm

Strength: Strong

Color: Red

H. Diseases:

Corn Lethal Necrosis (MCMV=Maize Chlorotic Mottle Virus and MDMV=Maize Dwarf Mosaic Virus): Intermediate

Anthracnose Stalk Rot (C. graminicola): Resistant

N. Leaf Blight (E. turcicum): Intermediate Common Rust (P. sorghi): Resistant

Gray Leaf Spot (C. zeae): Intermediate

Goss's Wilt (C. nebraskense): Highly Resistant

Head Smut (S. reiliana): Highly Resistant

Fusarium Ear Mold (F. moniliforme): Susceptible

Gibberella Ear Rot (G. zeae): Intermediate

I. Insects:

European Corn Borer-1 Leaf Damage (Pre-flowering): Resistant

European Corn Borer-2 (Post-flowering): Resistant

The above descriptions are based on a scale of 1-9, 1 being highly susceptible, 9 being highly resistant.

S (Susceptible): Would generally represent a score of 1-3.

I (Intermediate): Would generally represent a score of 4-5.

R (Resistant): Would generally represent a score of 6-7.

H (Highly Resistant): Would generally represent a score of 8-9. Highly resistant does not imply the inbred is immune.

J. Variety Most Closely Resembling:

    ______________________________________     Character         Hybrid     Maturity          Pioneer Brand 3578     Usage             Pioneer Brand 3578     ______________________________________

Items B, C, D, E, F, and G are based on a maximum of two reps of data primarily from Johnston, Iowa in 1993.

EXAMPLE 1 Research Comparisons for Pioneer Hybrid 3531

Comparisons of the characteristics for Pioneer Brand Hybrid 3531 were made against Pioneer Brand Hybrids 3615, 3578 and 3563. Table 1A compares Pioneer Brand Hybrid 3531 and Pioneer Brand Hybrid 3615. The data shows 3531 has higher yield and grain harvest moisture than 3615. 3531 is a taller hybrid than 3615. 3531 sheds (GDU Shed) later than 3615.

Table 1B compares Pioneer Brand Hybrid 3531 to Pioneer Brand Hybrid 3578. The hybrids have similar yield, but 3531 has lower grain harvest moisture and a higher test weight. 3531 flowers (GDU Shed and GDU Silk) earlier than 3578. 3531 has better brittle stalk resistance than 3578.

The results in Table 1C show Pioneer Brand Hybrid 3531 has higher yield and grain harvest moisture but lower test weight than Pioneer Brand Hybrid 3563. 3531 is shorter hybrid with higher ear placement compared to 3563. 3531 flowers (GDU Shed and GDU Silk) earlier than 3563. 3531 has better stalk lodging resistance than 3563.

                                      TABLE 1A     __________________________________________________________________________     VARIETY #1 - 3531     VARIETY #2 - 3615                  BU   BU        PLT  EAR DRP GDU  TST STA RT  BRT             VAR  ACR  ACR  MST  HT   HT  EAR SHD  WTA GRN LDG STK             #    ABS  % MN ABS  ABS  ABS ABS ABS  ABS ABS ABS ABS     __________________________________________________________________________     TOTAL SUM             1   127.9 103  23.3 102.8                                      51.0                                          99.9                                              1215 55.0                                                       92.1                                                           99.4                                                               97.3             2   115.3 93   22.3 99.0 51.0                                          99.9                                              1195 55.0                                                       94.0                                                           100.0                                                               97.0             LOCS                 12    12   12   2    2   12  2    11  11  12  4             REPS                 22    22   23   4    4   23  4    21  21  23  7             DIFF                 12.6  10   1.1  3.8  0.0 0.0 20   0.0 1.9 0.6 0.2             PROB                 .007# .011+                            .028+                                 .126 1.00                                          1.00                                              .500 .994                                                       .229                                                           .197                                                               .860     __________________________________________________________________________      * = 10% SIG      + = 5% SIG      # = 1% SIG

                                      TABLE 1B     __________________________________________________________________________     VARIETY #1 - 3531     VARIETY #2 - 3578     __________________________________________________________________________                 BU  BU       PLT EAR SDG EST  DRP GDU   GDU   TST             VAR ACR ACR MST  HT  HT  VGR CNT  EAR SHD   SLK   WTA             #   ABS % MN                         ABS  ABS ABS ABS ABS  ABS ABS   ABS   ABS     __________________________________________________________________________     TOTAL SUM             1   149.4                     107 26.2 104.0                                  47.9                                      5.5 62.7 99.5                                                   1246  1229  52.8             2   147.9                     106 26.9 104.7                                  47.8                                      5.3 61.8 99.7                                                   1259  1247  52.4             LOCS                 219 219 221  93  90  83  110  128 66    23    195             REPS                 278 278 281  112 109 103 132  168 86    25    250             DIFF                 1.5 1   0.7  0.7 0.1 0.2 0.9  0.2 13    18    0.4             PROB                 .139                     .182                         .000#                              .117                                  .872                                      .179                                          .037+                                               .108                                                   .000# .003# .000#     __________________________________________________________________________                                              GRN  STA STK RT   BRT                                           VAR                                              APP  GRN LDG LDG  STK                                           #  ABS  ABS ABS ABS  ABS     __________________________________________________________________________                                    TOTAL SUM                                           1  6.0  5.2 95.5                                                           96.3 95.9                                           2  5.8  5.9 97.2                                                           98.1 93.2                                           LOCS                                              95   67  192 114  44                                           REPS                                              116  83  245 152  51                                           DIFF                                              0.2  0.7 1.7 1.8  2.8                                           PROB                                              .190 .001#                                                       .000#                                                           .024+                                                                .062*     __________________________________________________________________________      * = 10% SIG      + = 5% SIG      # = 1% SIG

                                      TABLE 1C     __________________________________________________________________________     VARIETY #1 - 3531     VARIETY #2 - 3563     __________________________________________________________________________                 BU   BU        PLT  EAR  SDG  EST DRP  GDU   GDU             VAR ACR  ACR  MST  HT   HT   VGR  CNT EAR  SHD   SLK             #   ABS  % MN ABS  ABS  ABS  ABS  ABS ABS  ABS   ABS     __________________________________________________________________________     TOTAL SUM             1   146.5                      108  25.6 103.9                                     46.7 5.4  61.1                                                   99.5 1260  1234             2   131.3                      96   23.9 106.5                                     44.7 5.7  61.0                                                   99.8 1301  1279             LOCS                 334  334  340  168  165  157  203 178  108   32             REPS                 394  394  401  188  185  176  227 213  130   35             DIFF                 15.1 12   1.8  2.6  2.0  0.3  0.1 0.3  41    45             PROB                 .000#                      .000#                           .000#                                .000#                                     .000#                                          .012+                                               .795                                                   .013+                                                        .000# .000#     __________________________________________________________________________                                         TST  GRN STA   STK                                                           RT   BRT                                      VAR                                         WTA  APP GRN   LDG                                                           LDG  STK                                      #  ABS  ABS ABS   ABS                                                           ABS  ABS     __________________________________________________________________________                             TOTAL SUM                                      1  52.8 6.1 4.8   95.1                                                           95.7 96.8                                      2  54.2 6.1 4.9   94.2                                                           96.7 96.7                                      LOCS                                         300  149 131   303                                                           144  73                                      REPS                                         355  167 150   356                                                           185  81                                      DIFF                                         1.4  0.0 0.1   0.9                                                           1.0  0.0                                      PROB                                         .000#                                              .822                                                  .516  .042+                                                           .225 .971     __________________________________________________________________________      * = 10% SIG      + = 5% SIG      # = 1% SIG

EXAMPLE 2 Strip Test Data for Hybrid 3531

Comparison data was collected from strip tests that were grown by farmers. Each hybrid was grown in strips of 4, 6, 8, 12, etc. rows in fields depending on the size of the planter used. The data was collected from strip tests that had the hybrids in the same area and weighed. The moisture percentage was determined and bushels per acre was adjusted to 15.5 percent moisture. The number of comparisons represent the number of locations or replications for the two hybrids that were grown in the same field in close proximity and compared.

Comparison strip testing was done between Pioneer Brand Hybrid 3531 and Pioneer Brand Hybrids 3615, 3578 and 3563. The comparisons came from all the hybrid's adapted growing areas in the United States.

These results are presented in Table 2. 3531 has a yield advantage over all of the hybrids. 3531 has a moisture advantage over 3578. 3531 showed a greater income advantage to the farmer based on adjusted growth income over all hybrids compared. The income per acre advantage ranged from $4.26 to $21.86. 3531's yield and income advantage plus its advantage for other characteristics over these hybrids will make it an important addition for most of the areas where these hybrids are grown.

                                      TABLE 2     __________________________________________________________________________     PIONEER HYBRID 3531 VS PIONEER HYBRIDS 3615, 3578 AND 3563     FROM 1993 STRIP TESTS                               Income/                                    Pop  Stand                                             Roots                                                 Test     Brand        Product                       Yield                           Moist                               Acre K/Acre                                         (%) (%) Wt     __________________________________________________________________________     PIONEER      3531 117.8                           24.9                               243.45                                    20.7 87  99  50.7     PIONEER      3615 104.6                           22.6                               221.59                                    20.3 94  100 52.0     Advantage         13.2                           -2.3                               21.86                                    0.4  -7  -1  -1.3     Number of Comparisons                       19  19  19   7    6   5   18     Percent Wins      78  5   78   42   33  0   11     Probability of Difference                       99  99  99   35   75  63  99     PIONEER      3531 126.5                           27.6                               255.76                                    27.2 83  91  49.1     PIONEER      3578 125.9                           29.1                               251.50                                    26.8 95  92  49.1     Advantage         0.6 1.5 4.26 0.4  -12 -1  0.0     Number of Comparisons                       158 158 158  108  96  82  151     Percent Wins      55  74  62   53   22  8   38     Probability of Difference                       49  99  98   95   90  14  13     PIONEER      3531 134.7                           23.0                               283.63                                    25.9 88  93  52.1     PIONEER      3563 125.0                           21.3                               267.86                                    26.0 83  94  54.2     Advantage         9.7 -1.7                               15.77                                    -0.1 5   -1  -2.1     Number of Comparisons                       709 709 709  379  313 230 594     Percent Wins      74  15  69   37   55  9   4     Probability of Difference                       99  99  99   85   99  91  99     PIONEER      3531 132.9                           23.9                               277.80                                    26.1 87  92  51.5     WEIGHTED AVG      124.7                           22.7                               263.95                                    26.1 86  93  53.1     Advantage         8.2 -1.2                               13.85                                    0.0  1   -1  -1.6     Number of Comparisons                       886 886 886  494  415 317 763     Percent Wins      71  25  68   40   47  8   11     Probability of Difference                       99  99  99   32   47  82  99     __________________________________________________________________________

EXAMPLE 3 Comparison of Key Characteristics for Hybrid 3531

Characteristics of Pioneer Brand Hybrid 3531 are compared to Pioneer Brand Hybrids 3615, 3578 and 3563 in Table 3. The ratings given for most of the traits are on a 1-9 basis. In these cases 9 would be outstanding, while 1 would be poor for the given characteristics. These values are based on performance of a given hybrid relative to other Pioneer commercial, precommercial and competitive hybrids that are grown in research and strip test trials. The traits characterized in Table 3 were defined previously and the ratings utilized not only research data but experience trained corn researchers had in the field as well as sales experience with the hybrids in strip tests and the field. These scores reflect the hybrids relative performance to other hybrids for the characteristics listed. Table 3 shows 3531 yielded well for its maturity. 3531 has good drydown and seedling vigor when compared to the other hybrids. 3531 has better brittle stalk resistance compared to the other hybrids. 3531 has overall excellent yield and agronomic characteristics which should make it an important hybrid in its area of adaptation.

    __________________________________________________________________________     HYBRID PATENT COMPARISONS - CHARACTERISTICS     Pioneer Hybrid 3531 vs Pioneer Hybrids 3615, 3578 and 3563     __________________________________________________________________________     HYBRID           SILK CRM                  GDU SILK                         BL CRM                              GDU BL                                   CRM YLD                                          H/POP                                               L/POP                                                   D/D                                                      S/L                                                         R/L                                                            STGR                                                                D/T     __________________________________________________________________________     3531  102    1300   103  2610 105 9  --   --  6  5  4  5   6     3615  105    1340   102  2580 102    6    7   7  4  7  4   7     3578  103    1320   103  2610 104 8  8    8   5  7  6  6   5     3563  106    1350   105  2660 103 8  8    7   5  6  6  6   7     __________________________________________________________________________                                    HYBRID                                          T/WT                                              G/A                                                 E/G                                                    P/HT                                                        E/HT                                                            D/E B/STK     __________________________________________________________________________                                    3531  4   4  7  6   6   5   6                                    3615  4   4  7  5   6   7   5                                    3578  4   4  5  6   5   4   4                                    3563  7   7  4  7   4   7   5     __________________________________________________________________________

INDUSTRIAL APPLICABILITY

This invention includes hybrid corn seed of 3531 and the hybrid corn plant produced therefrom. The foregoing was set forth by way of example and is not intended to limit the scope of the invention.

As used herein, the term plant includes plant cells, plant protoplasts, plant cell tissue cultures from which corn plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants or parts of plants, such as embryos, pollen, flowers, kernels, ears, cobs, leaves, husks, stalks, roots, root tips, anthers, silk and the like.

Duncan, Williams, Zehr, and Widholm, Planta, (1985) 165:322-332 reflects that 97% of the plants cultured which produced callus were capable of plant regeneration. Subsequent experiments with both inbreds and hybrids produced 91% regenerable callus which produced plants. In a further study in 1988, Songstad, Duncan & Widholm in Plant Cell Reports (1988), 7:262-265 reports several media additions which enhance regenerability of callus of two inbred lines. Other published reports also indicated that "nontraditional" tissues are capable of producing somatic embryogenesis and plant regeneration. K. P. Rao, et al., Maize Genetics Cooperation Newsletter, 60:64-65 (1986), refers to somatic embryogenesis from glume callus cultures and B. V. Conger, et al., Plant Cell Reports, 6:345-347 (1987) indicates somatic embryogenesis from the tissue cultures of maize leaf segments. Thus, it is clear from the literature that the state of the art is such that these methods of obtaining plants are, and were, "conventional" in the sense that they are routinely used and have a very high rate of success.

Tissue culture of corn is described in European Patent Application, publication 160,390, incorporated herein by reference. Corn tissue culture procedures are also described in Green and Rhodes, "Plant Regeneration in Tissue Culture of Maize," Maize for Biological Research (Plant Molecular Biology Association, Charlottesville, Va. 1982, at 367-372) and in Duncan, et al., "The Production of Callus Capable of Plant Regeneration from Immature Embryos of Numerous Zea Mays Genotypes," 165 Planta 322-332 (1985). Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce corn plants having the genotype of 3531.

Corn is used as human food, livestock feed, and as raw material in industry. The food uses of corn, in addition to human consumption of corn kernels, include both products of dry- and wet-milling industries. The principal products of corn dry milling are grits, meal and flour. The corn wet-milling industry can provide corn starch, corn syrups, and dextrose for food use. Corn oil is recovered from corn germ, which is a by-product of both dry- and wet-milling industries.

Corn, including both grain and non-grain portions of the plant, is also used extensively as livestock feed, primarily for beef cattle, dairy cattle, hogs, and poultry.

Industrial uses of corn are mainly from corn starch in the wet-milling industry and corn flour in the dry-milling industry. The industrial applications of corn starch and flour are based on functional properties, such as viscosity, film formation, adhesive properties, and ability to suspend particles. The corn starch and flour have application in the paper and textile industries. Other industrial uses include applications in adhesives, building materials, foundry binders, laundry starches, explosives, oil-well muds, and other mining applications.

Plant parts other than the grain of corn are also used in industry. Stalks and husks are made into paper and wallboard and cobs are used for fuel and to make charcoal.

The seed of the hybrid corn plant and various parts of the hybrid corn plant can be utilized for human food, livestock feed, and as a raw material in industry.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity and understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the invention, as limited only by the scope of the appended claims.

DEPOSITS

Applicant has made a deposit of at least 2500 seeds of Hybrid 3531 with the American Type Culture Collection (ATCC), Rockville, Md. 20852 USA, ATCC Deposit No. 97164. The seeds deposited with the ATCC on May 25, 1995 were taken from the deposit maintained by Pioneer Hi-Bred International, Inc., 700 Capital Square, 400 Locust Street, Des Moines, Iowa 50309-2340 since prior to the filing date of this application. This deposit of the Hybrid 3531 will be maintained in the ATCC depository, which is a public depository, for a period of 30 years, or 5 years after the most recent request, or for the effective life of the patent, whichever is longer, and will be replaced if it becomes nonviable during that period. Additionally, Applicant has satisfied all the requirements of 37 C.F.R. §§1.801-1.809, including providing an indication of the viability of the sample. Applicant imposes no restrictions on the availability of the deposited material from the ATCC; however, Applicant has no authority to waive any restrictions imposed by law on the transfer of biological material or its transportation in commerce. Applicant does not waive any infringement of rights granted under this patent.

Applicant has made a deposit of at least 2500 seeds of Inbred Corn Line PHP55 with the American Type Culture Collection (ATCC), Rockville, Md. 20852 USA, ATCC Deposit No. 75220. The seeds deposited with the ATCC on Mar. 20, 1992, were taken from the deposit maintained by Pioneer Hi-Bred International, Inc., 700 Capital Square, 400 Locust Street, Des Moines, Iowa 50309-2340 since prior to the filing date of this application. This deposit of the Inbred Corn Line PHP55 will be maintained in the ATCC depository, which is a public depository, for a period of 30 years, or 5 years after the most recent request, or for the effective life of the patent, whichever is longer, and will be replaced if it becomes nonviable during that period. Additionally, Applicant has satisfied all the requirements of 37 C.F.R. §§1.801-1.809, including providing an indication of the viability of the sample. Applicant imposes no restrictions on the availability of the deposited material from the ATCC; however, Applicant has no authority to waive any restrictions imposed by law on the transfer of biological material or its transportation in commerce. Applicant does not waive any infringement of rights granted under this patent or under the Plant Variety Protection Act (7 USC 2321 et seq.). PHP55 is a U.S. Protected Variety under Plant Variety Protection Certificate No. 8900318. PHP55 is described sufficiently to identify it and to permit examination in Plant Variety Protection Certificate No. 8900318 and in U.S. Pat. No. 5,159,134, "Inbred Corn Line PHP55", issued on Oct. 27, 1992.

Applicant has made a deposit of at least 2500 seeds of Inbred Corn Line PHTE4 with the American Type Culture Collection (ATCC), Rockville, Md. 20852 USA, ATCC Deposit No. 97065. The seeds deposited with the ATCC on Feb. 22, 1995 were taken from the deposit maintained by Pioneer Hi-Bred International, Inc., 700 Capital Square, 400 Locust Street, Des Moines, Iowa 50309-2340 since prior to the filing date of this application. This deposit of the Inbred Corn Line PHTE4 will be maintained in the ATCC depository, which is a public depository, for a period of 30 years, or 5 years after the most recent request, or for the effective life of the patent, whichever is longer, and will be replaced if it becomes nonviable during that period. Additionally, Applicant has satisfied all the requirements of 37 C.F.R. §§1.801-1.809, including providing an indication of the viability of the sample. Applicant imposes no restrictions on the availability of the deposited material from the ATCC; however, Applicant has no authority to waive any restrictions imposed by law on the transfer of biological material or its transportation in commerce. Applicant does not waive any infringement of rights granted under this patent or under the Plant Variety Protection Act (7 USC 2321 et seq.). PHTE4 is a U.S. Protected Variety under Plant Variety Protection Certificate No. 9400094. PHTE4 is described sufficiently to identify it and to permit examination in Plant Variety Protection Certificate No. 9400094 and in U.S. Pat. No. 5,453,564 to be issued Sep. 26, 1995, "Inbred Corn Line PHTE4", and in co-pending patent applications, Ser. No. 08/414,477 filed Mar. 31, 1995 and Ser. No. 08/500,286 filed Jul. 10, 1995. 

What is claimed is:
 1. Hybrid corn seed designated 3531, the seed of which have been deposited and have ATCC accession No.
 97164. 2. A hybrid corn plant and its parts produced by the seed of claim
 1. 3. A tissue culture of regenerable cells of a hybrid corn plant produced by hybrid corn seed designated 3531, the seed of which have been deposited and have ATCC accession No. 97164, wherein the tissue culture regenerates plants having all of the physiological and morphological characteristics of hybrid corn plant
 3531. 4. A tissue culture according to claim 3, the tissue culture selected from the group consisting of leaves, pollen, embryos, roots, root tips, anthers, silks, flowers, kernels, ears, cobs, husks, stalks, and cells and protoplasts thereof.
 5. A corn plant regenerated from the tissue culture of claim 3, the regenerated corn plant having all of the physiological and morphological characteristics of hybrid corn plant
 3531. 